2L 170 CR DIESEL
the past few months whilst motorway driving, the car never gets up to temperature. it goes up when under load and drops when coasting. When in traffic it reaches 90 degrees and stays there. never overheats. obvious answer is a thermostat stuck open. Main dealer diagnosed a faulty thermostat and replaced it. however the problem still remains. they had it in the workshop for a further day and are now telling me there is an additional thermostat in the system that 'could' be causing the issue. i've never heard of 2 thermostats in a system. why would you need 2?? any suggestions gratefully received. Thanks